JP5040804B2 - Semiconductor device manufacturing method and semiconductor element inspection structure - Google Patents

Description

  The present invention relates to a method for manufacturing a semiconductor device in which semiconductor elements are mounted face-down on a wiring board, and a semiconductor element inspection structure.

  As the functions and performance of various electronic devices improve, flip-chip mounting is adopted in which bare chips, which are semiconductor elements without molds, are mounted face-down on a wiring board in order to bring out the performance of the electronic devices used. Examples are increasing. This is because there is no case resistance compared to a structure in which the mounted semiconductor element is accommodated in the case and mounted on the wiring board, so that the case has no resistance and can cope with higher-speed signals.

  In flip chip mounting, as shown in the schematic cross-sectional view of FIG. 2A, an electronic circuit is formed on the lower surface of a silicon wafer or the like, and an electrode (not shown) for connecting the electronic circuit and the wiring board is formed on the lower surface. The formed semiconductor element 2 for face-down mounting is used. A metal projection (bump 3) such as a solder called a bump is provided on an electrode (not shown) of the semiconductor element 2, and this is face-down opposed to the wiring board 4, and the bump 3 is melted and joined to the electrode of the wiring board 4. The electrodes of the semiconductor element 2 and the wiring board 4 are connected via bumps 3. High-density mounting is possible compared to wire bonding mounting.

In the bare chip mounting, as shown in FIG. 2B, an underfill resin 5 is provided between the semiconductor element 2 and the wiring board 4 in order to relieve stress caused by a difference in thermal expansion coefficient between the semiconductor element 2 and the wiring board 4. A filling structure is employed (see Patent Document 1).
In addition, since the underfill resin 5 is made of a high-strength resin in order to ensure the reliability of the semiconductor element 2 and the wiring substrate 4, the semiconductor element 2 cannot be replaced after the underfill resin 5 is filled. . Therefore, the bare chip inspection after the bare chip mounting is performed without filling the underfill resin 5 in order to allow the semiconductor element 2 to be replaced.

Further, as shown in FIG. 3, the semiconductor element 2 that generates a large amount of heat is made of a material having high thermal conductivity such as aluminum or copper. A heat sink 6 is attached and inspected to keep the ambient temperature below a certain level.
With the increase in size of the semiconductor element 2, a gap is generated between the semiconductor element 2 and the heat sink 6 for reasons such as warpage of the semiconductor element 2, and it is difficult to bring the heat sink 6 and the semiconductor element 2 into close contact with each other. . For this reason, the gap between the semiconductor element 2 and the heat sink 6 is filled with a thermally conductive filling layer 7 made of a material having thermal conductivity such as thermal grease or a thermally conductive compound (see Patent Document 2).
JP 2001-291805 A JP-A-57-208149

  In the semiconductor element inspection after the bare chip mounting, since there is a gap between the semiconductor element 2 and the wiring board 4, as shown in FIG. 3, a thermally conductive filling layer 7 such as grease that fills the gap between the heat sink 6 and the semiconductor element 2, etc. May penetrate into this gap. Once the grease or the like has entered, it cannot be completely removed by washing, and voids are generated when the underfill resin 5 is filled, resulting in a problem that the reliability of the semiconductor device is deteriorated due to poor adhesion.

  In order to prevent the heat conductive filling layer 7 such as grease from entering the gap between the semiconductor element 2 and the wiring substrate 4, a heat conductive sheet 8 having low fluidity may be used as shown in FIG. Since the conductive sheet 8 has a high thermal resistance and the semiconductor element cooling performance decreases, there is a problem that the power of the semiconductor element must be limited.

  An object of the present invention is to provide a method of manufacturing a semiconductor device capable of suppressing the occurrence of voids in an underfill resin due to the entry of foreign matter such as grease into the gap between a semiconductor element and a wiring board, which is the problem described above. It is in.

  Another object of the present invention is to provide a semiconductor element inspection structure capable of suppressing the occurrence of voids in the underfill resin caused by foreign matter such as grease entering the gap between the semiconductor element and the wiring board, which is the problem described above. It is to provide.

  In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention includes a mounting step of mounting a semiconductor element face down on a wiring board, and a protective part made of a material that can be washed and removed around the semiconductor element. A protection part forming step for filling the gap between the semiconductor element and the wiring substrate; an inspection step for performing an operation inspection of the semiconductor element and a connection inspection between the semiconductor element and the wiring substrate; and And a protective part removing step for washing and removing.

  Further, the semiconductor element inspection structure of the present invention includes a wiring board, a semiconductor element mounted face down on the wiring board, and the semiconductor element and the wiring board around the semiconductor element with a material that can be cleaned and removed. And a protective part formed by filling the gap.

  According to the method for manufacturing a semiconductor device of the present invention, after mounting the semiconductor element on the wiring board in a face-down manner, the protective portion made of a material that can be washed and removed around the semiconductor element is provided with a gap between the wiring board and the wiring board. By filling and forming, even if the subsequent thermal grease or thermal conductive compound is applied to the surface of the semiconductor element, the protective part prevents them from entering the gap between the semiconductor element and the wiring board in the inspection process. be able to. After the inspection process, the grease and the protective part can be washed away to prevent the residue from remaining in the gap between the semiconductor element and the wiring board, so when filling the gap between the semiconductor element and the wiring board with underfill resin, Since there is no obstacle, it can suppress that a void generate | occur | produces. As a result, it is possible to manufacture a highly reliable semiconductor device by firmly fixing the semiconductor element to the wiring board with an underfill resin having no voids.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
1A to 1E are cross-sectional views of a semiconductor device sequentially illustrating steps of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

A semiconductor device 1a shown in FIG. 1A shows a flip chip mounting structure in which a bare chip semiconductor element 2 is mounted face-down on a wiring substrate 4 via bumps 3.
The semiconductor element 2 is provided with a transistor or the like for processing an electric signal on a semiconductor substrate such as silicon, and is connected to each other by wiring such as aluminum. On the surface of the semiconductor element 2, exposed electrodes (not shown) of a rewiring layer drawn out to a place to be electrically connected to the outside are provided, for example, in a matrix arrangement.
Bumps 3 are formed on the electrodes as protrusions for metal bonding to the electrodes of the wiring board 4.

  The bump 3 is formed by a method in which an adhesive layer or a diffusion prevention layer is provided on the aluminum electrode and the bump 3 is formed by electroplating, a method in which a ball bump is formed on the aluminum electrode by using a ball bonding method, aluminum There are a method of forming bumps on an electrode by electroless plating, a method of forming a metal that gets wet with solder on an aluminum electrode, and then immersing it in a molten solder bath, a physical film forming method, and the like. As a material of the bump 3, a solder made of gold, copper, nickel, tin, lead, indium or the like can be used alone, or two or more kinds of bumps can be laminated.

For the wiring board 4, glass, ceramic, glass epoxy, polyimide, phenol resin, or the like can be used.
The wiring pattern formed on the wiring board 4 includes nickel, copper, titanium, ITO (indium tin oxide), chromium, aluminum, molybdenum, tantalum, tungsten, gold, silver alone, an alloy thereof or a combination thereof. It can be formed by a method such as sputtering, vapor deposition, plating and printing using a metal material.
For example, an internal connection terminal (not shown) on which a solder paste is printed is provided at the position of the wiring pattern corresponding to the position where the bump 3 of the semiconductor element 2 is located.

In the face-down mounting process, for example, the internal connection terminals of the wiring board 4 and the bumps 3 of the semiconductor element 2 are mounted in alignment with each other, and solder paste is melted through a reflow furnace to form a solder joint.
Thereby, the semiconductor device 1a in which the semiconductor element 2 and the wiring board 4 are electrically connected via the bumps 3 can be obtained.

When the semiconductor device 1a mounted face down is found to be abnormal when an inspection is found and the semiconductor element 2 needs to be replaced, the gap between the semiconductor element 2 and the wiring board 4 can be changed. Prior to the process of filling the fill resin, an inspection process of the semiconductor device 1a is performed.
Furthermore, in the present invention, a protective part forming step is performed before the inspection step.

In the protective part forming step, as shown in FIG. 1B, a protective part 9 that fills the gap between the entire periphery of the semiconductor element 2 and the wiring substrate 4 is formed.
The protection unit 9 has a function of preventing foreign matter from entering the gap between the wiring board 4 and the semiconductor element 2.
Therefore, the protection unit 9 is formed so as to fill the gap between the peripheral edge of the semiconductor element 2 that is the entrance of the gap between the semiconductor element 2 and the wiring board 4 and the wiring board 4. Further, it may be formed so as to fill all the gaps between the semiconductor element 2 and the wiring board 4.

The material constituting the protective part 9 needs to be removable by washing, and it is desirable that the material can be easily removed without leaving a trace before filling with the underfill resin.
Therefore, it is desirable to use a material that can be washed and removed with water or a material that can be washed and removed with an organic solvent.
In addition, materials that can be removed by washing with an aqueous alkali solution or washed with an aqueous acid solution can also be used.

Examples of the material that can be washed and removed with water include polyvinyl alcohol, starch, and a water-soluble resin for paper processing.
Examples of the material soluble in the organic solvent include polyvinyl acetate and polystyrene.
Examples of the alkali-soluble material include a resin having a carboxyl group or a sulfonic acid group.
Examples of the acid-soluble material include mono- or dimethylaminoethyl ester, mono- or diethylaminoethyl ester of acrylic acid or methacrylic acid.
In the current production process of semiconductor devices, water cleaning and cleaning using an aqueous solvent are mainly used. Therefore, a material that can be cleaned and removed with water can be preferably used.

The protective part 9 is formed by, for example, extruding a viscous aqueous solution containing polyvinyl alcohol from a thin nozzle between the peripheral edge of the semiconductor element 2 and the wiring substrate 4, and the peripheral edge of the semiconductor element 2 and the wiring substrate 4. A liquid protection portion for filling the gap between the semiconductor element 2 and the wiring board 4 is formed on the entire periphery so as to surround the semiconductor element 2 while filling the gap with an aqueous polyvinyl alcohol solution.
Next, the protective part 9 which is cured by heating the liquid protective part to evaporate water is formed. In this case, since the protective part 9 is only required to prevent foreign matter from entering the gap between the semiconductor element 2 and the wiring board 4, it is not necessary to cure to the inside, and partial curing of only the surface may be used. By using partial curing, cleaning and removal are facilitated.
Since the cured protective part 9 contains polyvinyl alcohol, it can be easily washed away with water.

The semiconductor device 1b thus obtained is a semiconductor element inspection structure according to the present invention. The semiconductor device 1b has a wiring substrate 4, a semiconductor element 2 mounted face-down on the wiring substrate 4, and a semiconductor that can be cleaned and removed. It has a structure having a protective portion 9 formed by filling the gap between the semiconductor element 2 and the wiring substrate 4 around the element 2.
The protection unit 9 can prevent foreign matter from entering the gap between the semiconductor element 2 and the wiring board 4 in the inspection process.

Before the inspection process, as shown in FIG. 1C, in order to prevent the semiconductor element 2 having a large electric power and a large calorific value from becoming high temperature during the inspection process, a desired inspection can be performed. There may be a heat sink installation step of temporarily installing the heat sink 10 for inspection on the surface of the semiconductor element 2.
In recent years, with an increase in size of the semiconductor element 2, a gap is generated between the semiconductor element 2 and the heat sink 10 due to warpage of the semiconductor element 2, and it becomes difficult to make the heat sink 10 and the semiconductor element 2 adhere to each other. ing.
Therefore, in the heat sink installation step, a heat conductive filling layer 11 is provided to fill a gap between the semiconductor element 2 and the heat sink 10 with a material having thermal conductivity such as thermal grease or a heat conductive compound, and the heat generated by the heat sink 10. It is done to improve the emission of

In the inspection process, an operation inspection of the semiconductor element 2 and a connection inspection between the semiconductor element 2 and the wiring board 4 are performed.
If it is necessary to replace the defective semiconductor element 2 at this time, the semiconductor element 2 can be easily replaced because it is not bonded to the wiring board 4 with the underfill resin.
The inspection process is performed, for example, by setting the wiring board 4 on which the semiconductor element 2 is mounted on a prober.

  In the heat sink installation process or the inspection process, the semiconductor device 1c shown in FIG. 1C is provided with the protective portion 9 formed by filling the gap between the semiconductor element 2 and the wiring board 4 around the semiconductor element 2. Even if the fluid heat conductive filler layer 11 filled between the heat sink 10 and the semiconductor element 2 flows down, the heat conductive filler layer 11 enters the gap between the semiconductor element 2 and the wiring substrate 4 by the protection unit 9. Can be prevented.

After the inspection process, the heat sink is removed and the thermal grease 11 is washed away with an organic solvent, and the protective part 9 is further washed away with water in the protective part removing process.
As a cleaning method, for example, a method of cleaning by immersing the wiring board 4 on which the semiconductor element 2 is mounted in a cleaning liquid and applying ultrasonic waves can be employed.
As a result, as shown in FIG. 1D, an inspected face-down mounting structure 1d in which there is nothing other than the bump 3 in the gap between the semiconductor element 2 and the wiring board 4 is realized.

In the next underfill resin filling step, the underfill resin 5 is filled into the gap between the semiconductor element 2 and the wiring board 4 by, for example, being extruded from a thin nozzle.
Examples of the underfill resin include a liquid heat or ultraviolet curable resin composition containing an inorganic filler.
The blending of the inorganic filler can reduce the coefficient of thermal expansion and suppress the generation of voids.
As the inorganic filler, for example, Al ₂ O ₃ , MgO, BN, AlN, SiO ₂ or the like can be used. Moreover, as a thermosetting resin, an epoxy resin, a phenol resin, cyanate resin, or polyphenylene ether resin can be used. From the viewpoint of heat resistance, an epoxy resin can be preferably used.

  In the underfill resin filling process, no thermal grease or the like remains in the gap between the semiconductor element 2 and the wiring board 4 and there is nothing other than the bump 3, so that the liquid curable property is formed in the gap between the semiconductor element 2 and the wiring board 4. When the resin composition is injected, the liquid curable resin composition is filled in the gap between the semiconductor element 2 and the wiring substrate 4 without a gap by capillary action, and generation of voids is suppressed as much as possible.

After the underfill resin filling step, the underfill resin is heated or cured by irradiating ultraviolet rays, and the semiconductor element 2 is adhered to the wiring board 4 with the underfill resin 5 filled in the gap between the semiconductor element 2 and the wiring board 4. .
Since the semiconductor element 2 and the wiring board 4 are fixed by the underfill resin 5, the thermal expansion difference between the semiconductor element 2 and the wiring board 4 is absorbed by warp deformation, and a large shearing stress or tensile stress is not generated in the bump 3, thus causing disconnection failure The life to reach is greatly improved.

  As described above, the semiconductor device 1e manufactured by the semiconductor device manufacturing method according to the present embodiment has the underfill resin 5 filled in the gap between the semiconductor element 2 face-down mounted on the wiring board 4 and the wiring board 4. Since the generation of voids is suppressed as much as possible, a sufficient bonding strength of the underfill resin 5 can be obtained, and a semiconductor device having a high connection reliability between the semiconductor element 2 and the wiring substrate 4 can be provided. Can do.

The present invention is not limited to the embodiment described above.
For example, the protective part only needs to be washable and removable, and may be a putty-like material that does not harden.

The semiconductor device manufacturing method of the present invention can manufacture a flip-chip mounted semiconductor device with high connection reliability.
In addition, the semiconductor element inspection structure of the present invention can manufacture a semiconductor device that does not deteriorate the connection reliability in the inspection process of a flip-chip mounted semiconductor device.

(A)-(e) is sectional drawing of the semiconductor device which shows the process of the manufacturing method of the semiconductor device which concerns on one Embodiment of this invention sequentially. (A) is a schematic sectional drawing of the semiconductor device by which the flip chip mounting was carried out, (b) is a schematic sectional drawing which shows the semiconductor device filled with underfill resin. It is a schematic sectional drawing which shows the state in which thermal grease etc. penetrate | invaded into the clearance gap between a semiconductor element and a wiring board. It is a schematic sectional drawing which shows the semiconductor device using a heat conductive sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a-1e Semiconductor device 2 Semiconductor element 3 Bump 4 Wiring board 5 Underfill resin 9 Protection part 10 Heat sink 11 Thermally conductive filling layer

Claims (7)

Mounting process for mounting semiconductor elements face-down on a wiring board;
A protective part forming step of forming a protective part made of a material that can be washed and removed around the semiconductor element by filling a gap between the semiconductor element and the wiring board;
An inspection process for performing an operation inspection of the semiconductor element and a connection inspection between the semiconductor element and the wiring board;
A protective part removing step for washing and removing the protective part;
Before the inspection step, a heat sink installation step of installing a heat sink on the surface of the semiconductor element,
A method for manufacturing a semiconductor device, comprising:   2. The method of manufacturing a semiconductor device according to claim 1, further comprising an underfill filling step of filling an underfill resin in a gap between the wiring board and the semiconductor element after the protective part removing step. The method according to claim 1, wherein further comprising the step of providing a thermally conductive filler layer between said heat sink and said semiconductor element. 4. The method of manufacturing a semiconductor device according to claim 3 , further comprising a step of removing the installed heat sink and the thermally conductive filling layer after the inspection step. The protective portion is water-soluble, a manufacturing method of an oil-soluble, the semiconductor device of any one of claims 1 to 4, characterized in that it is composed of a material of an alkali-soluble or acid-soluble. 6. The method of manufacturing a semiconductor device according to claim 5, wherein the protective part contains polyvinyl alcohol. A wiring board; a semiconductor element mounted face-down on the wiring board; and a protective part formed by filling a gap between the semiconductor element and the wiring board around the semiconductor element with a material that can be cleaned and removed. and it has a,
A semiconductor element inspection structure, wherein a heat sink is installed on the semiconductor element via a thermally conductive filling layer .

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